Use gpu::Mailbox instead of std:string in IPCs

content/browser/renderer_host/render_widget_host_view_aura.h

Index: content/browser/renderer_host/render_widget_host_view_aura.h
diff --git a/content/browser/renderer_host/render_widget_host_view_aura.h b/content/browser/renderer_host/render_widget_host_view_aura.h
index 3c3757de81d9d921fc9d8f3d0f13f0c37b8d7742..0e01067735ead8f145d98e4b1beed3fa50f98728 100644
--- a/content/browser/renderer_host/render_widget_host_view_aura.h
+++ b/content/browser/renderer_host/render_widget_host_view_aura.h
@@ -60,6 +60,10 @@ class Canvas;
 class Display;
 }
 
+namespace gpu {
+struct Mailbox;
+}
+
 namespace ui {
 class CompositorLock;
 class CompositorVSyncManager;
@@ -530,14 +534,14 @@ class CONTENT_EXPORT RenderWidgetHostViewAura
   void BuffersSwapped(const gfx::Size& surface_size,
                       const gfx::Rect& damage_rect,
                       float surface_scale_factor,
-                      const std::string& mailbox_name,
+                      const gpu::Mailbox& mailbox,
                       const std::vector<ui::LatencyInfo>& latency_info,
                       const BufferPresentedCallback& ack_callback);
 
   bool SwapBuffersPrepare(const gfx::Rect& surface_rect,
                           float surface_scale_factor,
                           const gfx::Rect& damage_rect,
-                          const std::string& mailbox_name,
+                          const gpu::Mailbox& mailbox,
                           const BufferPresentedCallback& ack_callback);
 
   void SwapBuffersCompleted(